Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

979
FXUS63 KLOT 081127
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
627 AM CDT Wed Apr 8 2026

.KEY MESSAGES...

- Windy and warmer today, with gusts up to 40 mph this
  afternoon especially across north-central IL.

- Milder with periods of showers and some thunderstorms tonight
  into early Friday, and again from later in the weekend into
  early next week.

- Combined rainfall amounts tonight through Friday may exceed an
  inch across portions of the forecast area. This could produce
  new rises on area rivers and creeks.

&&

.DISCUSSION...
Issued at 330 AM CDT Wed Apr 8 2026

A northwest-southeast oriented area of light rain showers,
mixed with some light sleet/wet snow initially, was moving
across northeast Illinois north of I-80 as of 2:30 am. This was
occurring in association with warm advection on the nose of a
strengthening low-level jet, downstream of a low-amplitude short
wave and elevated warm front propagating through the region. At
the surface, winds have turned southeast overnight allowing
temperatures to rise into the mid-upper 30s (coolest north where
precipitation is occurring), so no impacts are expected in the
way of freezing rain, and any sleet/snow should be short lived
and non-accumulating. Precipitation should taper to spotty rain
sprinkles by sunrise, and end shortly after.

Otherwise, early morning surface analysis places ~1000 mb low
pressure over southwest South Dakota near the Nebraska border. A
surface warm front extends southeast from the low, across
eastern Nebraska and Kansas west of the Missouri River. The
surface low is forecast to lift quickly northeast into the upper
Mississippi Valley today, combining with deeper low pressure
developing toward the northwest shore of Lake Superior by early
this evening. In the process, the warm front will lift quickly
north across the forecast area early this afternoon, with a
windy warm sector air mass spreading across the area. Decreasing
cloud cover by this afternoon should help temperatures to surge
into the mid-upper 60s across the area, with a few spots
tagging 70 degrees across our western cwa. Southwest winds will
gust as high as 35 to 40 mph, especially across north-central IL
where the the gradient will be a little stronger. Some higher
gusts are possible late this afternoon, especially if boundary
layer mixing ends up deeper than currently expected.

As the aforementioned surface low tracks north of Lake Superior
tonight, it will trail a slow-moving cold front southeast
across the area. A line of showers and isolated/embedded
thunderstorms along and ahead of the front will move into north-
central IL mid-late evening, and slowly work its way east-
southeast across the area overnight as the front slowly
advances. Forecast QPF amounts are generally in the 0.25-0.30
inch range, focused across the northern half of the cwa. Showers
shift south of I-80 Thursday morning, weakening as stronger
forcing passes off to the northeast and the front slows its
southward push, stalling across or just south of the southern
cwa Thursday evening. Another mid-level shortwave is progged to
transit the region Thursday night into Friday morning however,
inducing redevelopment of another round of showers and
thunderstorms along/north of the frontal zone. This is
accompanied by an axis of deeper moisture (PWATs over 1.25"),
which looks to produce greater rainfall amounts (generally
0.50-075"+) across the forecast area. Exact location of higher
amounts is of low confidence just yet, though combined QPF from
tonight and Thursday night/Friday in excess of an inch appears
possible. This would likely cause additional rises on area
rivers which are still in flood stage in some locations due to
previous heavy rains.

Surface high pressure is progged to build across the upper
Midwest and Great Lakes region Friday night into Saturday,
pushing the front south of the area and allowing for at least a
brief respite from additional rainfall.

Global ensemble guidance continues to show good agreement in
the upper pattern becoming more amplified from this weekend into
early next week, as a deep west-coast long wave trough develops
and induces southwest flow downstream into the Midwest and
Great Lakes region. Return of warmer/moist air aloft appears to
bring rain chances back to the forecast area as early as
Saturday night with the returning warm front and indications of
a low-amplitude mid-level wave emerging from the base of the
western upper trough. This looks to begin a period warmer but
also more active weather from Sunday into early next week.

Ratzer

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 627 AM CDT Wed Apr 8 2026

Key Aviation Messages for the current TAF period:

- Gusty southeast winds will switch to the southwest around
  midday. Max wind gusts this afternoon are expected to exceed
  30 knots.

- Better chances for rain overnight tomorrow night.

The main impact at area terminals today will be from strong
wind gusts. Wind directions will start this morning out of the
southeast and slowly veer to the southwest around midday. Gusts
25 to 30 knots can be expected through the day, but peak wind
gusts in excess of 30 knots are expected this afternoon. As a
low level jet intensifies after 00Z, there is a chance for low
level wind shear concerns if surface winds decouple. For now
surface gusts should remain strong enough to prohibit shear
inclusion in the TAF.

As a surface low moves eastward over southern Canada tonight,
it will send a front across the upper midwest and drive a line
of showers across the region. There is a non-zero chance for
thunder, but with the probability less than 30 percent
presently it was kept out of the TAF and will be monitored.
Wind gusts will gradually diminish behind the rain and become
more west-southwesterly.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 4 AM CDT Thursday for the IL
     nearshore waters.

     Small Craft Advisory until 7 AM CDT Thursday for the IN
     nearshore waters.

&&

$$

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